YS/T 273.5-2006Chemical analysis methods and physical properties of cryolite. Part 5: Determination of sodium by flame atomic absorption spectrometric method (English PDF)

589.0 nm to the hypo-sensitive 589.6 nm;

-- The length of the working curve is shortened, and the concentration of the highest

concentration standard solution in the working curve is reduced from 10.0

µg/mL to 5.00 µg/mL;

Chemical analysis methods and physical properties of

cryolite - Part 5.Determination of sodium by flame atomic

absorption spectrometric method

3.1 Sulfuric acid (rho 1.84 g/mL).

3.2 Hydrochloric acid (rho 1.19 g/mL).

3.3 Sodium standard solution. Weigh 3.089 g of anhydrous sodium sulfate that has been

dried at 120 °C and cooled in a desiccator, place it in a 250 mL beaker, and add 100 mL

of water to dissolve; then, add 10 mL of hydrochloric acid (3.2), transfer the solution to

a 1000 mL volumetric flask, dilute to volume with water, mix well, and transfer it to a

polyethylene bottle. 1 mL of this solution contains 1.000 mg of sodium.

4.1 Platinum dish. The diameter is 80 mm, and the height is 35 mm.

4.2 Atomic absorption spectrometer. It is equipped with a sodium hollow cathode lamp.

Any instrument that can meet the following indicators under the best working

conditions can be used.

-- Characteristic concentration. In a solution consistent with the matrix of the

measured sample, the characteristic concentration of sodium shall not be greater

than 0.07 ug/mL.

-- Precision. Use the standard solution with the highest concentration to measure

the absorbance 10 times, and the standard deviation shall not exceed 1.0% of

the average absorbance; use the standard solution with the lowest concentration

(not the "zero" concentration standard solution) to measure the absorbance 10

times, and the standard deviation shall not exceed 0.5% of the average

absorbance of the highest concentration standard solution.

-- Working curve linearity. Divide the working curve into 5 equal segments

according to concentration, and the ratio of the absorbance difference in the

highest segment to the absorbance difference in the lowest segment is not less

than 0.85.

6.1 Test portion

Weigh 0.5 g of test sample (5), accurate to 0.0001 g.

6.2 Number of determinations

Two determinations shall be carried out independently and the average value shall be

taken.

6.3 Blank test

Do a blank test along with the sample test.

6.4 Determination

6.4.1 Place the test portion (6.1) in the platinum dish (4.1), add 5 mL of sulfuric acid

(3.1), and slowly dissolve it in a sand bath (15 min~20 min) to remove fluorine; then,

heat it to evaporate until the thick smoke emits; remove the test portion and cool it to

room temperature; add 3 mL of hydrochloric acid (3.2) and 30 mL of water, and heat in

a low-temperature sand bath until all salts are dissolved. After cooling, transfer the

solution to a 500 mL volumetric flask, dilute to volume with water, and mix well.

6.4.2 According to Table 1, take the test solution (6.4.1), place it in a 500 mL volumetric

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